P1539: SEASONALITY OF HEALTHCARE RESOURCE UTILIZATION AMONG COLD AGGLUTININ DISEASE AMONG PATIENTS IN DENMARK: A RETROSPECTIVE ANALYSIS
Authors: J. Fryzek, N. Hooda, B. Öztürk Esen, T. Sourdille, E. Horváth-Puhó, E. K. Vago, C. Broome, A. Röth
Journal: HemaSphere (2022)

Background: Cold agglutinin disease (CAD) is a rare form of autoimmune hemolytic anemia characterized by monoclonal autoantibodies targeting red blood cell (RBC) surface structures, preferentially at lower temperatures (Berentsen et al. Hematol Oncol Clin North Am, 2015). This results in both agglutination of RBCs and complement-mediated hemolysis. Patients with CAD were previously shown to have a greater healthcare utilization compared to the general population (Vago. CurMedRes, 2021). Considering exposure to cold temperatures may precipitate both the circulatory symptoms of CAD and hemolysis (Berentsen. Br J Haematol, 2018), understanding seasonal variation of CAD manifestations may be important to guide nonpharmacological management strategies and prophylactic recommendations (Lyckholm et al. N Engl J Med, 1996; Berentsen et al. Hematology, 2007). A previous retrospective cohort in the United States demonstrated persistent hemolysis independent of the season with disease manifestations, as evaluated by healthcare resource utilization (HRU) (Röth et al. Transfusion, 2022). Aims: This study sought to elucidate the effects of seasonal temperature on the HRU of patients with CAD by comparing fall (September-November), winter (December-February), spring (March-May), and summer (June-August) values for inpatient admissions and outpatient visits in the first year after diagnosis or cohort entry and for the entire follow-up period with a matched comparison cohort in Denmark. Methods: Patients were retrospectively identified using ICD-10 codes from the Danish National Patient Registry with linkage to multiple databases including the Danish Civil Registration System and the Danish Register of Causes of Death. Crude numbers of HRU were determined by the number of inpatient admissions and outpatient visits in the first year after diagnosis or cohort entry and for the entire follow-up period for each season. Results: We identified 72 patients diagnosed with CAD and 720 matched comparisons, matched for age, gender, and region of residence, between 1999 and 2013. Inpatient stays and outpatient visits were higher for CAD patients than their matched comparisons for all seasons. Further there were no substantial differences between spring, summer, fall, and winter in CAD-related inpatient stays (40.3%, 31.9%, 36.1% and 36.1%, respectively) and outpatient visits (72.2% and 70.8%, 77.8% and 73.6%, respectively) during the entire duration of follow-up (Table 1). Results remained consistent in the first year after diagnosis or cohort entry wherein proportion of CAD patients with inpatient visits ranged from 19.4% in summer to 23.6% in winter and outpatient visits ranged from 62.5% in spring and fall to 63.9% in winter. Image:Summary/Conclusion: Patients with CAD in this cohort had evidence of persistent HRU independent of the season. These data do not support perceptions of CAD as a seasonal disorder; recommendations such as moving to regions with warmer climates may not provide meaningful clinical benefit. The lack of seasonal variability in this cohort suggests that treatment considerations for patients with CAD should be season-independent.